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Abstract:

Methods of the invention include those for applying protective sheets to
articles. According to these methods and resulting articles, a protective
sheet is applied to at least a portion of an exterior surface where
protection is desired on an article. At least one portion of at least one
exterior surface of the article to be protected can be integrally formed
in the presence of the protective sheet. Improved bonding of the
protective sheet to the article and improved processing efficiency are
advantageously achieved according to the invention.

Claims:

1. An article comprising a protective sheet integrally bonded to at least
one portion thereof.

2. The article of claim 1, wherein the article is fully covered by the
protective sheet.

3. The article of claim 1, wherein the article comprises at least a
portion of a motorized vehicle.

4. The article of claim 3, wherein the article comprises a bumper.

5. The article of claim 1, wherein the article comprises at least a
portion of an aerospace component.

19. The article of claim 1, wherein the protective sheet has a chip
resistance rating of at better than "6B" as measured according to ASTM
D3170 (SAE J400).

20. The article of claim 1, wherein the protective sheet is bonded to an
underlying surface of the article without an adhesive therebetween.

21. An article comprising a protective sheet adhered to at least one
exterior portion thereof, wherein the protective sheet provides all
desired enhancements in performance and aesthetic properties of the
article in one protective sheet component as compared to use of multiple
protective sheet or protective coating components.

22. A method of applying a protective sheet to at least a portion of an
exterior surface of an article, the method comprising:providing the
protective sheet prior to forming at least one exterior surface of the
article; andintegrally forming the at least one exterior surface of the
article in the presence of the protective sheet such that at least a
portion of the exterior surface of the article and at least a portion of
the protective sheet become integrally bonded.

23. The method of claim 22, wherein the exterior surface of the article is
formed using an in-mold processing or insert-mold processing technique.

24. The method of claim 22, wherein the exterior surface of the article is
formed using an injection molding technique.

25. A method of applying a protective sheet to at least a portion of an
exterior surface of an article, the method comprising:providing the
protective sheet;forming the exterior surface of the article;
andco-molding the protective sheet to the exterior surface of the article
such that at least a portion of the exterior surface of the article and
at least a portion of the protective sheet become integrally bonded.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001]This application is a continuation-in-part of PCT Patent Application
No. PCT/US06/60160, filed on Oct. 23, 2006, which claims the benefit of
U.S. Provisional Patent Application No. 60/728,987, filed on Oct. 21,
2005, both of which are hereby incorporated by reference in their
entirety.

BACKGROUND OF THE INVENTION

[0002]The present invention relates generally to articles comprising
protective sheets, as well as methods of making and using the same.

[0003]A variety of protective sheets and protective coatings can be
selectively applied to protect exterior surfaces on a variety of
articles. Often, protective sheets and protective coverings are
selectively applied to an article's surface after the article is formed.
Many such applications are intended to reduce abrasion or other wear on
the underlying surface. Other applications are geared primarily toward
maintaining or improving aesthetics or integrity of an underlying surface
(e.g., when the underlying surface contains printed material thereon or
when the surface contains aesthetically undesirable pinholes, bubbles, or
other surface imperfections that can occur when, for example, producing
molded articles). It is not surprising that there exists a need for
protective sheets and protective coatings in a variety of applications.

[0004]Certain protective sheets and protective coatings, as well as
related methods for making and using the same, are known. As an example,
polyurethane "clearcoat" protective coatings have been applied to a
variety of finished molded parts, such as plastic body panels, in order
to bolster weathering performance, as well as scratch- and
abrasion-resistance, without detrimentally affecting appearance of the
underlying surface. Another example involves application of polyurethane
sheets to automotive body panels for protection of the body panel against
chipping or other damage caused by, for example, objects such as flying
stones or debris. As another example, "leading edge tapes" have been
applied to select portions of articles, such as helicopter blades and
aircraft noses or wings, in order to protect underlying surfaces from
scratch- and abrasion-resistance.

[0005]There are two widely used methods of applying gel coats or similar
exterior protective coatings to articles. The first method involves
spraying the gel coat onto an exterior surface of an article after the
article is formed (e.g., by molding). The second method involves
eliminating this subsequent processing (e.g., post-molding) step by
pre-applying the gel coat to the interior surface of, for example, a mold
where it can then be transferred to an exterior surface of the article
formed therein. For example, see U.S. Pat. Nos. 4,081,578; 4,748,192; and
5,849,168. This method, which is one variation of "in-mold processing,"
is sometimes referred to as in-mold declaration or in-mold labeling
depending on the application and materials used.

[0006]While gel coats are capable of improving the aesthetics of surfaces
to which they are applied, they are often not capable of imparting some
or all of the desired performance properties. For example, gel coats are
often too thin or too hard to provide substantial levels of abrasion
resistance. Further, gel coats typically do not provide significant
impact resistance when used on certain articles. After extended use, gel
coats also have a tendency to crack, which enables water to penetrate
into articles on which they are applied. Over time, such water
penetration may lead to significant structural damage of the article.
When the article is subjected to freeze-thaw cycling (e.g., as with many
aerospace parts that undergo several freeze-thaw cycles in a single day
of operation), premature structural failure is often more rapid, as any
water trapped within the article will likely produce larger cracks and
similar internal damage based on such freeze-thaw cycling.

[0007]In addition to their inability to often provide desired performance
properties, use of gel coats typically decreases overall processing
efficiency. For example, if the gel coat is spray-applied to a surface in
a post-processing step, additional labor and manufacturing time is
required in conjunction therewith. Even when applied in-mold, for
example, typical gel coats require cure time after application to a mold
surface and before actual molding of the article. Such cure time can take
several hours, which is obviously undesirable from the perspective of
processing efficiency.

[0008]While in-mold processing is otherwise generally more efficient than
post-mold application of gel coats, if printed material (e.g., a textual
or graphical decal) is applied to the surface of a finished article, a
gel coat must then be conventionally spray-applied to that surface or a
protective coating or protective sheet must generally be applied over the
printed material as a post-processing step. This is often necessary even
if a gel coat has already been applied to the surface in-mold.

[0009]The types of materials that can be applied as a gel coat are also
limited, which is undesirable as it decreases flexibility in design and
manufacture of articles. For example, many conventional gel coat
materials are two-part compounds having a relatively short pot life,
which requires that they be used within a few hours of compounding or
discarded. When in-mold application of gel coats is desired, additional
constraints must be considered. For example, availability of certain
polymer matrix systems for in-mold processing, such as those based on
epoxy thermoset resins used with carbon fiber reinforcements, is very
limited.

[0010]It should be noted that materials other than gel coats have been
applied "in-mold" and to different types of underlying surfaces. For
example, multi-layer paint replacement film has been converted to a
finished product through an in-mold decoration process. This process
typically involves back molding of the film to form a finished article
having the paint replacement film integrally adhered to the outer
surface. In-mold processing has also been utilized to construct certain
specialized sporting implements such as bicycle helmets, where a foam
layer is in-mold bonded to the hard outer shell of the helmet.
Nevertheless, application of exterior protective coverings to surfaces is
in need of improvement.

[0011]To provide higher levels of abrasion resistance or impact resistance
beyond what gel coats alone can provide, protective sheets have been
added to the exterior surfaces of articles in addition to gel coats. As
compared to a protective coating, such as a gel coat, a protective sheet
is generally applied to a surface in its cured form. In contrast, a
coating is generally applied to a surface to be protected in an uncured
(e.g., solution) form, after which it is cured in-situ. While a sheet may
be formed using conventional extrusion, casting, or coating technology,
before the sheet is applied to a surface to be protected it is cured
and/or formed.

[0012]Conventional protective sheets are often applied to a surface using
a pressure sensitive adhesive. Many undesirable issues can arise,
however, if the pressure sensitive adhesive is not adequately designed
and formulated. For example, many pressure sensitive adhesives lack
adequate bond strength to prevent edge lifting of protective sheets that
are adhered to an underlying surface using the same. Protective sheets
applied using existing technologies are typically not permanently bonded
to the underlying surface. The durability of such constructions is often
short-lived, as the adhesive bond often fails during repeated use,
causing the protective sheet to lift from the surface. As another
example, many conventional pressure sensitive adhesives are either
repositionable and/or removable. This allows conventional protective
sheets, which may lack adequate extensibility for easy application to a
surface (especially irregular-shaped surfaces), to be more easily applied
to surfaces. However, such pressure sensitive adhesives typically lack
adequate permanency. In addition, often when a pressure sensitive
adhesive is used for bonding a protective sheet to an underlying surface,
a gel coat or other protective coating is often used in addition to the
protective sheet (e.g., a coating is applied to an underlying surface
before the protective sheet is applied).

[0013]In addition to the shortcomings associated with bonding of
protective sheets to an underlying surface, application of protective
sheets has proven to be otherwise difficult. For example, in addition to
the bonding issues arising based on the often inadequately extensible
nature of conventional protective sheets, it is often difficult to apply
protective sheets to surfaces with complex shapes when relatively thick
or multi-layer protective sheets are used. As a result, wrinkles often
exist in protective sheets so applied. Even if uniformly applied to
irregular surfaces initially, over time conventional protective sheets
are prone to lifting from such surfaces. In any event, the way in which
protective sheets are typically applied to such surfaces generally
decreases processing efficiency.

[0014]While some benefits can be obtained from application of protective
sheets and protective coatings according to known methods, such
conventional methods often result in articles that still fail to
adequately address important performance and processing considerations.
Not only are performance property considerations important, but for the
reasons stated above, aesthetics are also often another important
consideration.

[0015]When attempting to address the myriad of important considerations,
however, processing efficiency is often compromised. This is the case
when, for example, multiple protective sheets and/or protective coatings
(e.g., gel coats) are applied to a surface. In order to improve
processing efficiency, it is desirable to minimize the number of
protective sheets and protective coatings such as gel coats (especially
those gel coats used primarily for aesthetic enhancement) that are
applied to protect surfaces of underlying articles. For example, if gel
coats could be eliminated, processing efficiency could improve both in
terms of cost and time savings associated with the otherwise required
additional processing steps associated with gel coating.

BRIEF SUMMARY OF THE INVENTION

[0016]A wide variety of articles benefit from application of protective
sheets according to the invention. Articles of the invention are useful
in a range of indoor and outdoor applications--for example, the
transportation, architectural and sporting goods industries. In certain
embodiments of the invention, the article comprises at least a portion of
a motorized vehicle (e.g., a bumper or side view mirror enclosure), at
least a portion of an aerospace apparatus (e.g., a rotor blade for a
helicopter), or at least a portion of a sporting implement (e.g.,
bicycles, skis, snowboards, and the like). Protective sheets of the
invention have a chip resistance rating of at least "6B," preferably
better, as measured according to ASTM D3170 (SAE J400).

[0017]According to one aspect of the invention, an article comprises a
protective sheet integrally bonded to at least one portion thereof. In
one embodiment, the article has at least one exterior surface and the
protective sheet covers at least a portion of that exterior surface. In
another embodiment, the article is fully covered by the protective sheet.

[0018]According to another aspect of the invention, an article comprises
an exterior protective sheet adhered to an underlying surface, wherein
the article is essentially free of additional layers (e.g., an adhesive)
between the protective sheet and the underlying surface. According to yet
another aspect of the invention, an article comprises a protective sheet
adhered to at least one exterior portion thereof, wherein the protective
sheet is capable of providing all desired enhancements in performance and
aesthetic properties of the article in one protective sheet component as
compared to use of multiple protective sheet or protective coating
components.

[0019]In an exemplary embodiment, at least a portion of the protective
sheet is crosslinked with at least a portion of an underlying surface of
the article. The protective sheet can also undergo thermolysis during
cure of the article according to one aspect of the invention and
depending on materials used for the various components.

[0020]Any suitable materials can be used for the protective sheet or to
form the same. Preferably, the protective sheet is extensible. In an
exemplary embodiment, the protective sheet comprises at least one
elastomeric material. Protective sheets encompassed within the invention
comprise any suitable chemistry and components to provide protective
properties desired. For example, protective sheets can comprise
(meth)acrylate, polyester, silicone, polyvinyl chloride, polyolefin
(e.g., polyethylene, polypropylene, etc.), polyurethane, and/or
fluorinated chemistries. In an exemplary embodiment, the protective sheet
comprises at least one polyurethane-based layer.

[0021]Preferably, the protective sheet is visually clear. Thus, it is also
preferred that the protective sheet consists essentially of non-composite
material. According to further embodiments, the article comprises at
least one of printed material and graphical material on at least one
outwardly visible surface thereof.

[0022]Methods of the invention include those for applying protective
sheets of the invention to a variety of articles. According to these
methods, a protective sheet is applied to at least a portion of an
exterior surface where protection is desired on an article. According to
one embodiment of a method of the invention, at least one exterior
surface of the article to be protected is integrally formed in the
presence of the protective sheet.

[0023]One embodiment of a method of using a protective sheet to protect a
molded surface comprises steps of: providing the protective sheet prior
to forming the molded surface; and molding the surface in the presence of
the protective sheet such that the molded surface is integrally formed
with the protective sheet on at least a portion of at least one exterior
surface thereof.

[0024]Another embodiment of a method of using a protective sheet to
protect a molded surface comprises steps of: providing the protective
sheet; forming the molded surface; and co-molding the protective sheet on
at least a portion of the molded surface such that the protective sheet
is integrally bonded with the molded surface.

[0025]The molded surface can be integrally formed, for example, with the
protective sheet using an in-mold processing or insert-mold processing
technique, such as an injection molding technique. In-mold and
insert-mold processing for adherence of a protective sheet to an
article's surface facilitates formation of new and improved articles.
When formed in such a manner, beneficial properties associated with the
protective sheet being positioned on an exterior surface of the article
are maximized. For example, protective layers adhered to articles'
surfaces using conventional methods such as spray coating a protective
film using gel technology or otherwise adhering a protective film or
sheet to a formed surface (e.g., using an adhesive, thermal bonding, or
otherwise) are generally more prone to compromise beneficial protective
properties or even fail as compared to those protective sheets integrally
bonded to an article's surface. In addition, in-mold and insert-mold
processing results in manufacturing efficiencies realized by, for
example, elimination of process steps secondary to article formation as
well as elimination of adhesive bonding materials otherwise required in
many secondary applications.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026]FIG. 1 is a cross-sectional representation of an exemplary vacuum
bag processing configuration for application of protective sheets
according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0027]The present invention is directed toward improved articles
comprising a protective sheet on at least a portion of at least one
exterior surface thereof. The surface underlying the protective sheet can
comprise any suitable material or combinations thereof and may form any
useful article. For example, the surface underlying at least a portion of
the protective sheet can comprise a composite material as described in
PCT Patent Application No. PCT/US06/60160 filed on Oct. 23, 2006. While
certain advantages may be realized when at least a portion of the
underlying surface comprises a composite material, the underlying surface
may be any other suitable material in other embodiments of the invention.

[0028]Any suitable protective sheet can be applied to an article according
to methods of the invention in order to result in improved articles.
While a sheet material may be used primarily for aesthetic purposes
(e.g., adding color to a surface) in certain applications, such a purpose
or use does not exclude such sheets from being encompassed within the
definition of protective sheets referenced throughout in describing the
present invention. Preferred embodiments, however, are those associated
with protective sheets that are visually clear. In this regard, an
underlying surface to which the protective sheet is bonded can still be
viewed despite the presence of the protective sheet imparting certain
performance properties. Among other beneficial properties, the presence
of the protective sheet enhances durability (e.g., abrasion resistance)
of the article, as well as its impact resistance and fracture toughness
in further embodiments.

[0029]For example, protective sheets of the invention have a chip
resistance rating of at least "6B," preferably better, as measured
according to ASTM D3170 (SAE J400). According to this test method, an
approximately 10-centimeter (4-inch) by 30-centimeter (12-inch) sample of
protective sheet is mounted in back of a gravelometer, after which air
pressure is used to project about 300 pieces of gravel at the protective
sheet. The protective sheet is then removed and gently wiped with a clean
cloth. Tape is applied to the test surface and then removed to pull off
any loose fragments of the protective sheet. The appearance of the tested
sample is then compared to standard transparencies supplied by SAE
International to determine chipping ratings. Chipping ratings consist of
one or more letter-number combinations. The letter designates the chip
sizes being counted, and the number designates the number of chips of
that size. For example, a rating of "B6" indicates the presence of 10-24
chips 1-3 millimeters in size.

[0030]In addition to enhanced performance properties associated with
articles of the invention, processing efficiency is increased as compared
to conventional articles and methods. According to exemplary embodiments,
protective coatings (e.g., gel coats or similar protective coatings) are
not needed to obtain desired properties and, thus, can be eliminated from
articles of the invention. Such additional or inferior protective
coatings are capable of being eliminated as aesthetic enhancement is
typically not necessary in articles made according to the invention. As
such, even if conventional gel coats are used within articles of the
invention, aesthetics of the article would typically be essentially the
same as those of comparable articles without the gel coat.

[0031]In essence, protective sheets of the invention and methods of their
application are capable of providing all desired performance and
aesthetic properties in one component and without requiring use of
multiple protective sheets and/or multiple protective coatings in order
to obtain comparable properties. By eliminating undesirable protective
coatings and multiple protective layers, additional processing steps
associated with conventional methods for protection of surfaces are
likewise eliminated. Similarly, additional processing time associated
therewith, such as when a gel coat is applied in-mold in a way that
requires cure time after application to a mold surface and before actual
molding of the article, is also eliminated.

[0032]Even when printed material is included on an exterior surface of a
article, addition of a protective coating after application thereof to
the surface is not required according to an exemplary embodiment of the
invention. According to this embodiment, any printed material and/or
graphical material desired to be placed on an exterior surface of an
article is pre-printed onto or viewable within a protective sheet prior
to its bonding to the underlying article. The protective sheet is then
applied to at least a portion of a surface of an underlying article such
that the printed material and/or graphical material is outwardly visible.

[0034]An exemplary embodiment of the invention relates to sporting
implements and similar articles. Such articles include, for example, golf
clubs, bicycle components (e.g., frames), hockey sticks, lacrosse sticks,
skis, ski poles, fishing rods, tennis rackets, arrows, polo mallets, and
bats. According to a preferred aspect of this embodiment, the portion of
the surface where the protective sheet is applied is not the primary
surface for impact by a ball, puck, or other object (i.e., the surface is
not what may be commonly referred to as the "contact surface"). For
example, when the article is a hockey stick, the protective sheet is
preferably applied to the shaft as opposed to the blade. Similarly, when
the article is a golf club, the protective sheet is preferably applied to
the shaft as opposed to the club head. Likewise, when the article is a
lacrosse stick, the protective sheet is preferably applied to the handle
as opposed to the pocket. When the article is a baseball bat, the
protective sheet is preferably applied to the handle as opposed to the
barrel.

[0035]In certain applications, the presence of the protective sheet can
mean the difference between having a usable piece of sporting equipment
and/or one that is safe. For example, when a cross country skier's pole
breaks during a race they must either forfeit the race or be lucky enough
to be given another pole to use. As a further example, it is not uncommon
to break several hockey sticks during a game. Each time conventional
technology is used, the hockey stick has the potential to severely injure
another person or the player as its shape can readily transform into that
of a spear-like object when broken. By using articles of the present
invention, the equipment may still be usable (e.g., as in the case of the
cross country ski pole) or at least resist total failure for a longer
period of time. In addition, when articles of the present invention are
used, the equipment may be prevented from injuring somebody upon failure
(e.g., as in the case of a splintered hockey stick).

[0036]In certain embodiments, advantages of the invention are maximized
when the protective sheet is applied to substantially cover the entire
underlying surface. That is, the protective sheet fully covers the
underlying article. In comparison, partial coverage of an underlying
article may not adequately contain or prevent breakage of the overall
article in those applications. Thus, in an exemplary embodiment, the
protective sheet is applied to fully cover the underlying article or an
individual component thereof.

[0037]Performance benefits from the presence of the protective sheet are
enhanced when the protective sheet is integrally bonded to the article.
"Integrally bonded" refers to those materials with bonds formed between
the protective sheet and underlying article that are essentially
permanent in nature. Removal of an integrally bonded protective sheet
typically requires more force than that required to separate the same
protective sheet adhered using certain pressure sensitive adhesives
(e.g., those pressure sensitive adhesives having low shear and low tack,
removability, repositionability, or similar properties) that do not
facilitate formation of permanent or durable bonds. Integrally bonded
protective sheets are better able to contain underlying materials than
conventionally adhered protective sheets due to the reduced chances that
their bonds to underlying surfaces will fail.

[0038]According to the invention, at least one protective sheet is
integrally bonded to at least a portion of at least one surface of an
underlying article. Protective sheets of the invention are formed using
any suitable method. In one embodiment, the protective sheet is generally
planar. In exemplary embodiments, however, protective sheets are also
pre-formed into a shape approximating the shape of the surface onto which
it is to be adhered. This simplifies the process of adequately adhering
the protective sheet to the surface and can be done, for example, by
thermoforming or injection molding. Whatever the method used for its
fabrication, the protective sheet is formed separately from formation of
the exterior surface of the article to which it will be applied. Thus,
for example, protective sheets of the invention do not require, and
generally do not include, protective coatings formed by spray coating a
surface of an article with a composition that forms a protective layer on
the surface.

[0039]The protective sheet can be any suitable thickness. In one
embodiment, protective sheets of the invention are about 50 μm (0.002
inch) to about 1.1 mm (0.045 inch) thick at their maximum thickness. In a
further embodiment, protective sheets of the invention are about 80 μm
(0.003 inch) to about 0.64 mm (0.025 inch) thick at their maximum
thickness. In other embodiments, protective sheets of the invention are
greater than 0.51 mm (20 mils), or even greater than about 2.54 mm (100
mils) thick at their maximum thickness. In yet other embodiments,
protective sheets of the invention are thinner, ranging from about 0.15
mm (6 mils) to about 0.38 mm (15 mils) thick at their maximum thickness.
It has been found that the use of relatively thin protective sheets
imparts greater flexibility and conformability in many applications,
particularly when applying the protective sheet to an irregular-shaped
surface.

[0040]The protective sheet can be any suitable material and may include
one or more layers. Protective sheets of the invention comprise at least
a base layer and, optionally, topcoat or other layers. The use of
multiple layers within a protective sheet imparts flexibility in design
of protective sheets. While there may be protective sheets that do not
involve multiple layers, but rather one layer, certain performance
properties can often be better achieved when using a protective sheet
comprising multiple layers.

[0041]In an exemplary embodiment, the protective sheet comprises one or
more elastomeric materials. Elastomeric materials are preferably those
polymeric materials exhibiting about 200% or greater elastic elongation.
Elastomeric materials are preferred for use in the protective sheets of
the invention because such materials are highly resilient and exhibit
compressive recovery. Thus, elastomeric materials can enhance impact
resistance, abrasion resistance, and other similar performance properties
of surfaces and articles to which protective sheets comprising the same
are applied. Further, elastomeric materials are generally highly
extensible and conformable. Thus, when used in protective sheets of the
invention, such materials ease application of such protective sheets to
articles or molds of varying dimensions and shape. Exemplary elastomeric
films include those based on polyurethane, ionomer, and fluoroelastomer
chemistries. Extensible protective sheets are formed according to one
aspect of this embodiment.

[0042]The terms "extensible" and "extensibility" refer to a material's
ductility and its ability to be stretched and recover to essentially its
original state after stretching. Extensible protective sheets are capable
of recovering to their original state when stretched (i.e., elongated) up
to about 125% of their initial length or more. Preferably, extensible
protective sheets are capable of recovering to their original state when
stretched up to about 150% of their initial length or more. According to
one aspect of the invention, extensible protective sheets are capable of
elongating more than 200% before breaking. Further preferable are
extensible protective sheets that exhibit essentially no plastic
deformation when stretched up to about 150% of their initial length.

[0043]According to one aspect of the invention, extensible protective
sheets of the invention exhibit greater than about 210% elongation at
break when tested according to the Tensile Testing Method described
below. In a further embodiment, extensible protective sheets of the
invention exhibit greater than about 260% elongation at break when tested
according to the Tensile Testing Method described below. In a still
further embodiment, extensible protective sheets of the invention exhibit
greater than about 300% elongation at break when tested according to the
Tensile Testing Method described below. In a further embodiment still,
extensible protective sheets of the invention exhibit greater than about
350% elongation at break when tested according to the Tensile Testing
Method described below.

[0044]According to another aspect of the invention, extensible protective
sheets of the invention exhibit less than about 3% deformation after 25%
elongation when tested according to the Recovery Testing Method described
below. In a further embodiment, extensible protective sheets of the
invention exhibit less than about 2% deformation after 25% elongation
when tested according to the Recovery Testing Method described below. In
a still further embodiment, extensible protective sheets of the invention
exhibit less than about 1% deformation after 25% elongation when tested
according to the Recovery Testing Method described below.

[0045]According to another aspect of the invention, extensible protective
sheets of the invention exhibit less than about 8% deformation after 50%
elongation when tested according to the Recovery Testing Method described
below. In a further embodiment, extensible protective sheets of the
invention exhibit less than about 5% deformation after 50% elongation
when tested according to the Recovery Testing Method described below. In
a still further embodiment, extensible protective sheets of the invention
exhibit less than about 2% deformation after 50% elongation when tested
according to the Recovery Testing Method described below.

[0046]According to another aspect of the invention, extensible protective
sheets of the invention require a force of less than about 40 Newtons to
elongate the sheet to 150% its initial length. In a further embodiment,
extensible protective sheets of the invention require a force of less
than about 30 Newtons to elongate the sheet to 150% its initial length.
In yet a further embodiment, extensible protective sheets of the
invention require a force of less than about 20 Newtons to elongate the
sheet to 150% its initial length.

[0047]Protective sheets encompassed within the invention comprise any
suitable chemistry and components to provide aesthetic and performance
properties desired. For example, protective sheets can comprise
(meth)acrylate, polyester, silicone, polyvinyl chloride, polyolefin
(e.g., polyethylene, polypropylene, etc.), polyurethane, and/or
fluorinated chemistries. In an exemplary embodiment, protective sheets of
the invention are polyurethane-based in that they comprise at least one
polyurethane-based layer.

[0048]For simplicity, the term "polyurethane" as used herein includes
polymers containing urethane (also known as carbamate) linkages, urea
linkages, or combinations thereof (i.e., in the case of
poly(urethane-urea)s). Thus, polyurethanes of the invention contain at
least urethane linkages and, optionally, urea linkages. In one
embodiment, polyurethane-based layers of the invention are based on
polyurethanes where the backbone has at least about 80% urethane and/or
urea repeat linkages formed during their polymerization.

[0049]Polyurethane chemistry is well known to those of ordinary skill in
the art. Polyurethane-based layers of the invention can contain
polyurethane polymers of the same or different chemistries, the latter
commonly understood to be a polymer blend. Polyurethanes generally
comprise the reaction product of at least one isocyanate-reactive
component, at least one isocyanate-functional component, and one or more
other optional components such as emulsifiers and chain extending agents.

[0050]Components of polyurethanes are further described below, with
reference to certain terms understood by those in the chemical arts as
referring to certain hydrocarbon groups. Reference is also made
throughout to polymeric versions thereof. In that case, the prefix "poly"
is inserted in front of the name of the corresponding hydrocarbon group.
Except where otherwise noted, such hydrocarbon groups, as used herein,
may include one or more heteroatoms (e.g., oxygen, nitrogen, sulfur, or
halogen atoms), as well as functional groups (e.g., oxime, ester,
carbonate, amide, ether, urethane, urea, carbonyl groups, or mixtures
thereof).

[0051]The term "aliphatic group" means a saturated or unsaturated, linear,
branched, or cyclic hydrocarbon group. This term is used to encompass
alkylene (e.g., oxyalkylene), aralkylene, and cycloalkylene groups, for
example.

[0052]The term "alkylene group" means a saturated, linear or branched,
divalent hydrocarbon group. Particularly preferred alkylene groups are
oxyalkylene groups. The term "oxyalkylene group" means a saturated,
linear or branched, divalent hydrocarbon group with a terminal oxygen
atom. The term "aralkylene group" means a saturated, linear or branched,
divalent hydrocarbon group containing at least one aromatic group. The
term "cycloalkylene group" means a saturated, linear or branched,
divalent hydrocarbon group containing at least one cyclic group. The term
"oxycycloalkylene group" means a saturated, linear or branched, divalent
hydrocarbon group containing at least one cyclic group and a terminal
oxygen atom. The term "aromatic group" means a mononuclear aromatic
hydrocarbon group or polynuclear aromatic hydrocarbon group. The term
includes arylene groups. The term "arylene group" means a divalent
aromatic group.

[0053]Any suitable method can be used for preparation of polyurethanes for
use in polyurethane-based protective sheets of the invention. In one
embodiment, the polyurethane is prepared and formed into a single layer
using an extruder. The polyurethane can also be blown to form a single
layer.

[0054]Many commercially available polyurethanes are available and suitable
for use in preparing protective sheets of the invention. Extrusion grade
polyurethanes can be used in certain embodiments of the invention.
Extrusion grade polyurethanes include those available from Stevens
Urethane of Easthampton, Mass. Aliphatic polyurethanes from Stevens
Urethane, for example, those designated SS-1219-92 and SS-2219-92.
Suitable polyurethanes are also available from Thermedics (Noveon, Inc.)
of Wilmington, Mass., under the TECOFLEX trade designation (e.g.,
CLA-93AV) and from Bayer MaterialScience LLC of Pittsburgh, Pa., under
the TEXIN trade designation (e.g., aliphatic ester-based polyurethane
suitable as a base polymer for polyurethane-based layers of the invention
is available under the trade designation, TEXIN DP7-3008).
Polycaprolactone-based aliphatic polyurethane is available from Argotec,
Inc. of Greenfield, Mass. under the trade designation, ARGOTEC 49510.
Polyether-based aliphatic thermoplastic polyurethane is available from
Argotec, Inc. of Greenfield, Mass. under the trade designations, ARGOTEC
PE-399 and ARGOTEC PE-192. Similar polyurethanes are available from
Stephens Urethane of Easthampton, Mass., under the trade designations,
AG8451 and AG8320. Still further, similar polyurethanes are available
from Deerfield Urethane, Inc. of Whately, Mass. (a Bayer MaterialScience
company) under the trade designations Deerfield Urethane A4700 and
Deerfield Urethane A4100. Polyester-based aliphatic polyurethanes are
also suitable for use in the invention. Polycarbonate-based
polyurethanes, such as those described in U.S. Pat. No. 4,476,293 are
likewise suitable for use in the invention. In addition, U.S. Pat. Nos.
5,077,373 and 6,518,389 describe further suitable polyurethanes.

[0055]In another embodiment, polyurethane can be prepared and formed into
a single layer using solution or dispersion chemistry and coating
techniques known to those skilled in the art. Such a layer can be
prepared by reacting components, including at least one
isocyanate-reactive component, at least one isocyanate-functional
component, and, optionally, at least one reactive emulsifying compound,
to form an isocyanate-terminated polyurethane prepolymer. The
polyurethane prepolymer can then be dispersed, and optionally
chain-extended, in a dispersing medium to form a polyurethane-based
dispersion that can be cast to form a layer of polyurethane. When
polyurethane is prepared from an organic solventborne or waterborne
system, once the solution or dispersion is formed, it is easily applied
to a substrate and then dried to form a polyurethane layer. As known to
those of ordinary skill in the art, drying can be carried out either at
room temperature (i.e., about 20° C.) or at elevated temperatures
(e.g., about 25° C. to about 150° C.). For example, drying
can optionally include using forced air or a vacuum. This includes the
drying of static-coated substrates in ovens, such as forced air and
vacuum ovens, or drying of coated substrates that are continuously
conveyed through chambers heated by forced air, high-intensity lamps, and
the like. Drying may also be performed at reduced (i.e., less than
ambient) pressure.

[0056]Any suitable isocyanate-reactive component can be used in this
embodiment of the present invention. The isocyanate-reactive component
contains at least one isocyanate-reactive material or mixtures thereof.
As understood by one of ordinary skill in the art, an isocyanate-reactive
material includes at least one active hydrogen. Those of ordinary skill
in the polyurethane chemistry art will understand that a wide variety of
materials are suitable for this component. For example, amines, thiols,
and polyols are isocyanate-reactive materials.

[0057]It is preferred that the isocyanate-reactive material be a
hydroxy-functional material. Polyols are the preferred hydroxy-functional
material used in the present invention. Polyols provide urethane linkages
when reacted with an isocyanate-functional component, such as a
polyisocyanate.

[0059]Polycarbonate-based polyurethanes are preferred according to one
embodiment. It was found that this type of polyurethane chemistry easily
facilitated obtainment of polyurethane-based protective sheets with
properties desired. See U.S. Pat. No. 4,476,293 for a description of
exemplary polycarbonate-based polyurethanes.

[0060]In one preferred embodiment, a polycarbonate diol is used to prepare
polycarbonate-based polyurethane according to the invention. Although
polyols containing more than two hydroxy-functional groups are generally
less preferred than diols, certain higher functional polyols may also be
used in the present invention. These higher functional polyols may be
used alone, or in combination with other isocyanate-reactive materials,
for the isocyanate-reactive component.

[0061]For broader formulation latitude, at least two isocyanate-reactive
materials, such as polyols, may be used for the isocyanate-reactive
component. As any suitable isocyanate-reactive component can be used to
form the polyurethane, much latitude is provided in the overall
polyurethane chemistry.

[0062]The isocyanate-reactive component is reacted with an
isocyanate-functional component during formation of the polyurethane. The
isocyanate-functional component may contain one isocyanate-functional
material or mixtures thereof. Polyisocyanates, including derivatives
thereof (e.g., ureas, biurets, allophanates, dimers and trimers of
polyisocyanates, and mixtures thereof), (hereinafter collectively
referred to as "polyisocyanates") are the preferred isocyanate-functional
materials for the isocyanate-functional component. Polyisocyanates have
at least two isocyanate-functional groups and provide urethane linkages
when reacted with the preferred hydroxy-functional isocyanate-reactive
components. In one embodiment, polyisocyanates useful for preparing
polyurethanes are one or a combination of any of the aliphatic or
aromatic polyisocyanates commonly used to prepare polyurethanes.

[0065]When preparing polyurethane dispersions for casting into layers of
polyurethane, the isocyanate-reactive and isocyanate-functional
components may optionally be reacted with at least one reactive
emulsifying compound according to one embodiment of the invention. The
reactive emulsifying compound contains at least one anionic-functional
group, cationic-functional group, group that is capable of forming an
anionic-functional group or cationic-functional group, or mixtures
thereof. This compound acts as an internal emulsifier because it contains
at least one ionizable group. Thus, these compounds are generally
referred to as "reactive emulsifying compounds."

[0066]Reactive emulsifying compounds are capable of reacting with at least
one of the isocyanate-reactive and isocyanate-functional components to
become incorporated into the polyurethane. Thus, the reactive emulsifying
compound contains at least one, preferably at least two, isocyanate--or
active hydrogen-reactive--(e.g., hydroxy-reactive) groups. Isocyanate-
and hydroxy-reactive groups include, for example, isocyanate, hydroxyl,
mercapto, and amine groups.

[0067]Preferably, the reactive emulsifying compound contains at least one
anionic-functional group or group that is capable of forming such a group
(i.e., an anion-forming group) when reacted with the isocyanate-reactive
(e.g., polyol) and isocyanate-functional (e.g., polyisocyanate)
components. The anionic-functional or anion-forming groups of the
reactive emulsifying compound can be any suitable groups that contribute
to ionization of the reactive emulsifying compound. For example, suitable
groups include carboxylate, sulfate, sulfonate, phosphate, and similar
groups. As an example, dimethylolpropionic acid (DMPA) is a useful
reactive emulsifying compound. Furthermore, 2,2-dimethylolbutyric acid,
dihydroxymaleic acid, and sulfopolyester diol are other useful reactive
emulsifying compounds. Those of ordinary skill in the art will recognize
that a wide variety of reactive emulsifying compounds are useful in
preparing polyurethanes for the present invention.

[0068]One or more chain extenders can also be used in preparing
polyurethanes of the invention. For example, such chain extenders can be
any or a combination of the aliphatic polyols, aliphatic polyamines, or
aromatic polyamines conventionally used to prepare polyurethanes.

[0069]Illustrative of aliphatic polyols useful as chain extenders include
the following: 1,4-butanediol; ethylene glycol; 1,6-hexanediol;
glycerine; trimethylolpropane; pentaerythritol; 1,4-cyclohexane
dimethanol; and phenyl diethanolamine. Also note that diols such as
hydroquinone bis(β-hydroxyethyl)ether;
tetrachlorohydroquinone-1,4-bis(β-hydroxyethyl)ether; and
tetrachlorohydroquinone-1,4-bis(β-hydroxyethyl)sulfide, even though
they contain aromatic rings, are considered to be aliphatic polyols for
purposes of the invention. Aliphatic diols of 2-10 carbon atoms are
preferred. Especially preferred is 1,4-butanediol.

[0071]Any suitable additives can be present in protective sheets of the
invention. Many different types of additives can be used and are readily
available. For example, stabilizers, antioxidants, plasticizers,
tackifiers, adhesion promoters (e.g., silanes, glycidyl methacrylate, and
titanates), lubricants, colorants, pigments, dyes, polymeric additives
(e.g., polyacetals, reinforcing copolymers, and polycaprolactone diols),
and the like can be used in many embodiments of the invention. In certain
embodiments, however, use of additives detracting from optical clarity of
the protective sheet are minimized or eliminated. Such additives include,
for example, colorants, pigments, fillers, and fiber- or other
matrix-reinforcements typically present in composite materials. In an
exemplary embodiment, the protective sheet would not be considered to be
a composite material according to those skilled in the art.

[0072]According to another embodiment, polyurethane-based protective
sheets of the invention comprise multiple layers (e.g., a carrier and a
topcoat), at least one of which is polyurethane-based. According to one
variation of this embodiment, the carrier and the topcoat layers are both
polyurethane-based. In such an embodiment, the carrier preferably
comprises a polyurethane-based layer as discussed above with respect to a
single layer protective sheet of the invention. According to another
variation of this embodiment, polyurethane-based protective sheets of the
invention comprise a polyurethane-based topcoat and a carrier layer that
may or may not be polyurethane-based.

[0073]When forming a protective sheet comprising a topcoat layer, the
topcoat can be formed using any suitable method. In addition, the topcoat
can be crosslinked or uncrosslinked. An uncrosslinked topcoat can be
prepared from polyurethane-based layers discussed above. If crosslinking
is desired, any suitable method can be used for the same. An exemplary
discussion of crosslinked topcoats can be found in U.S. Pat. No.
6,383,644 and corresponding European Patent No. 1 004 608.

[0074]When applying the protective sheet to an article, particularly in
applications where the articles and respective processing equipment have
irregular-shaped or non-planar surfaces, extensibility of the protective
sheet is important. Protective sheets described in PCT Patent Application
No. PCT/US06/60171, entitled "Protective Sheets, Articles, and Methods,"
which is incorporated herein by reference in its entirety, were found to
be significantly more extensible than certain commercially available
protective sheets having a crosslinked topcoat. Accordingly, in a further
embodiment, protective sheets of the invention comprise an essentially
uncrosslinked topcoat. In many applications where protective sheets are
used, the potential benefits imparted by crosslinking an exterior layer
were substantially outweighed by the significantly improved extensibility
provided by protective sheets without a crosslinked exterior layer.

[0075]As discussed above, use of extensible protective sheets according to
an exemplary embodiment of the invention imparts significant advantages,
particularly when applying the protective sheet to irregular-shaped or
non-planar surfaces. Further, use of extensible protective sheets in this
manner better allows for full coverage of the article's outer surface
with the protective sheet in certain embodiments of the invention. As
noted above, full coverage can be beneficial for many applications in
enhancing containment of the underlying article so as to increase safety
and durability when using the article.

[0076]Several exemplary protective sheets applicable for use according to
the invention are readily available on the market today and can be
applied to the article without the additional use of a gel coat or
similar protective coating. For example, Minnesota Mining & Manufacturing
Co. ("3M") in St. Paul, Minn., markets polyurethane-based sheet "Paint
Protection Film" under the SCOTCHGARD product line. See also U.S. Pat.
No. 6,383,644. As another example, Venture Tape Corp. in Rockland, Mass.,
markets such sheets (e.g., designated by product numbers 7510, 7512, and
7514) using the VENTURESHIELD trade designation. Avery Dennison in
Strongsville, Ohio markets polyurethane products using the STONESHIELD
trade designation. Protective sheets are available from entrotech, inc.
of Columbus, Ohio under the ENTROFILM trade designations (e.g., entrofilm
843 and entrofilm 861) and others described in PCT Patent Application No.
PCT/US06/60171, entitled "Protective Sheets, Articles, and Methods."

[0077]According to the invention, a protective sheet is bonded to an
underlying article using any suitable method. For example, the protective
sheet can be adhered to an underlying article using an indirect bonding
method. When indirectly bonded, the protective sheet is adhered to the
underlying article using one or more additional layers therebetween. As
another example, the protective sheet can be directly bonded to the
exterior surface of an article. When directly bonded, the protective
sheet is adhered to the underlying surface of the article without the use
of any additional layers (e.g., adhesives, intermediate coatings, or tie
layers) therebetween. In this embodiment, it is to be understood that the
protective sheet itself preferably does not contain an outer adhesive
layer positioned in contact with the underlying surface to which it is
bonded according to the invention. For maximized process efficiency,
direct bonding methods are preferred.

[0078]The protective sheet can be applied to at least a portion of the
exterior surface of an article using in-mold, insert-mold, or co-mold
processing techniques. The latter is sometimes referred to in terms of
being a "reactive" molding technique.

[0079]In an exemplary embodiment, at least a portion of at least one
exterior surface of an article to be protected is integrally formed in
the presence of at least one protective sheet. "Integrally formed" refers
to those exterior surfaces that are molded or otherwise fabricated in the
presence of the protective sheet such that the two become integrally
bonded during such formation.

[0080]When the article is molded, the protective sheet can be applied
using in-mold, insert-mold, or co-mold processing techniques according to
this exemplary embodiment. When formed in such a manner, beneficial
properties associated with the protective sheet being positioned on an
exterior surface of the article are maximized, as protective sheets and
protective coatings adhered using other methods are generally more prone
to failure. In addition, in-mold, insert-mold, and co-mold processing
results in manufacturing efficiencies realized by, for example,
elimination of processing steps secondary to article formation and often
elimination of intermediate layers (e.g., those comprising adhesive
bonding materials) and associated processing steps in many applications.

[0081]As discussed above, a wide variety of materials can be used for
protective sheets of the invention. Extensible protective sheets, for
example, are readily adapted for in-mold, insert-mold and co-mold
processing techniques according to knowledge of those skilled in the art.
Significant advantages are imparted when using such exemplary methods.
For example, protective sheets applied using in-mold and insert-mold
processing techniques provide processing efficiencies and improved
performance properties arising from the improved integral bonding between
the protective sheet and underlying surface as compared to otherwise
adhering the protective sheet to the same surface after its formation.
Integral bonds achieved with in-mold and insert-mold processing result in
the protective sheet being less susceptible to shifting or sliding when
an article comprising the same is in use.

[0082]Similar enhancements are obtained when protective sheets of the
invention are co-molded with an article when applying a protective sheet
to the outer surface thereof. Co-molding, sometimes referred to as
reactive molding, refers to over-molding of an article with a protective
sheet by applying the protective sheet to a molded article's surface and
then further molding the article to sufficiently bond the protective
sheet to the article's surface.

[0083]When applying the protective sheet to a non-planar or
irregular-shaped surface of an article, it is not always necessary to
completely and precisely cover the surface with the protective sheet.
Rather, relatively small gaps in coverage (e.g., about 5 mm to about 10
mm) will often disappear after further molding of the article to
sufficiently bond the protective sheet to the article's surface. For
example, small gaps can disappear as a result of expansion of the
protective sheet under heat and/or pressure of the molding process.
Nevertheless, the protective sheet can overlap itself slightly (e.g., up
to about 10 mm) in other embodiments without significantly affecting the
resulting properties of the article comprising the protective sheet. In
such a case, a self-adhesive bond can develop at the weld seam comprising
the overlap. If desired, the weld seam of a co-molded article according
to the invention can be hot-pressed (e.g., using a hot roller at a
temperature of about 180° C.) to improve bonding at and appearance
of the weld seam.

[0084]When co-molding the protective sheet to an underlying article, an
adhesive may be included between the protective sheet and the underlying
surface to facilitate adequate bond formation. According to one aspect of
this embodiment, the adhesive is provided on the surface of the
protective sheet to be bonded to the underlying article. Preferably, such
an adhesive will be permanent in nature (e.g., such as that permanency
provided by a thermoset adhesives).

[0085]Each suitable processing technique is susceptible to many variations
as understood by those of ordinary skill in the art. For example, in-mold
and insert-mold processing, which involve placement in a mold of a
protective sheet to be integrally bonded with an article being formed
within the mold, can be done using a variety of molding techniques. Such
molding techniques include compression, bladder, vacuum bag, autoclave,
injection molding, resin transfer molding (RTM), vacuum-assisted RTM, and
other similar methods known to those of ordinary skill in the art.

[0086]With compression, bladder, vacuum bag, autoclave, and similar
methods, a protective sheet is first positioned within a suitable mold.
Material from which the article is to be formed is then positioned within
the mold for curing into the desired shape. During such curing, which is
often effected using heat and pressure, the protective sheet becomes
integrally bonded to at least a portion of at least one surface of the
article. According to a particularly preferred further embodiment,
crosslinks form between the protective sheet and at least a portion of
the underlying surface of the article during curing.

[0087]With injection molding, RTM, vacuum-assisted RTM, and similar
methods, a protective sheet is placed within a mold. Material from which
the article is to be formed is then injected into the mold to form an
article of the invention. Those of ordinary skill in the art are readily
familiar with injectable materials and techniques for their use in
injection molding. The injectable material itself is generally heated to,
for example, a semi-molten state for injection molding. For purposes of
this invention, the term "semi-molten" means capable of flowing into the
molding area. Prior to and during injection of the material, the
protective sheet can be stabilized within the mold using any suitable
method and apparatus, including the many methods associated with in-mold
decoration. Such methods include those using gravity, air pressure, pins,
tape, static electricity, vacuum, and/or other suitable means. In
addition, release agents and other molding components can be used as
readily understood by those skilled in the art.

[0088]Although not required, according to one variation of this
embodiment, the protective sheet is heated prior to injecting the
material into the mold and against the backside of the protective sheet.
For example, one variation of this embodiment relates to insert-mold
processing. During insert-mold processing, as compared to in-mold
processing, the protective sheet is thermoformed into a three-dimensional
shape prior to injection of the material. Typically, the protective sheet
is shaped to approximate the contour of the interior surface of the mold
into which it is placed for injection molding. In an exemplary
embodiment, the thermoforming step occurs within the mold such that it
does not require transfer prior to injection of the material. During
in-mold processing, the protective sheet changes shape, if at all, upon
injection molding of the material.

[0089]According to one aspect of this embodiment, any suitable injection
molding apparatus can be used for molding. Typically, such molding
apparatus have one or more orifices for injection of material into the
mold. According to injection molding, RTM and similar methods, with the
mold closed, uncured material (e.g., thermoset resin) is injected into
the mold, after which it flows under heat and pressure while curing.
Pressure from injecting material into the mold combined with the
temperature within the mold and the surface of associated mold parts
causes the material to fuse together with or bond to the interior surface
of the protective sheet (i.e., it becomes integrally bonded).

[0090]An exemplary method of the invention comprises a bladder mold
process. According to this embodiment, material for formation of an
article and a protective sheet are arranged and then wrapped together
around a bladder with a small mandrel inside the bladder. A heated mold
is then placed over the wrapped bladder, the bladder is expanded to force
the material against the mold, and the material forming the article is
then cured in the mold. Curing times and temperatures depend on the
specific materials used and are well known to those of skill in the art.
Extensible protective sheets described herein are preferred for use in
this embodiment, as such protective sheets are able to be efficiently and
sufficiently wrapped around the bladder in such a process.

[0091]In another exemplary method of the invention, vacuum bag processing
techniques are used to integrally bond protective sheets through in-mold
processing. During vacuum bag processing, an uncured material for
formation of the article is compacted against a mold surface to form an
assembly. A vacuum is then pulled across the entire assembly and mold to
remove excess air, uncured material, or other volatiles from the
assembly. While the vacuum is being pulled, the mold is heated to cure
the material within. According to a preferred embodiment, the vacuum
itself provides all the pressure necessary to effect full cure of the
material forming the article.

[0092]FIG. 1 is a cross-sectional representation of an exemplary vacuum
bag in-mold processing configuration for application of protective sheets
102 of the invention. Although the protective sheet 102 is illustrated as
a single layer, as discussed above, the protective sheet may actually
consist of multiple layers. The protective sheet 102 is placed against
the surface of the mold 104. As known in the art, the mold 104 may
optionally have a release agent applied to its surface in order to assist
with removal of the final article from the mold 104 after the in-mold
process is complete. On the opposite side of protective sheet 102, one or
more layers of uncured material 106 are positioned in contact with the
protective sheet 102. On the opposite side of the one or more layers of
uncured material 106, a peel ply release layer 108 is positioned. The
peel ply release layer 108 is typically porous or perforated to allow
excess uncured material to flow out of and to be removed from the
article. Opposite the peel ply release layer 108, a bleeder fabric layer
110 is positioned to absorb excess uncured material flowing through the
peel ply release layer 108. Opposite the bleeder fabric layer 110, a
separator release layer 112 is positioned to prevent excess uncured
material from flowing into an adjacent breather fabric layer 114. The
separator release layer 112 is often perforated to provide an air channel
for the vacuum into the breather fabric layer 114. The breather fabric
layer 114 is positioned opposite the separator release layer 112 and
wraps around the other layers to extend to the vacuum nozzle port 116.
The breather fabric layer 114 provides an air channel from the article to
the vacuum nozzle port 116. The entire assembly is sealed within a vacuum
by using sealant 120 to seal a vacuum bagging film 118 against the
surface of the mold 104. By operatively coupling a vacuum pump (not
shown) to the vacuum nozzle port 116, air can be removed from within the
entire vacuum bag assembly. This compresses the vacuum bagging film 118
against all other layers in the assembly to exert pressure against the
surface of mold 104. A vacuum of between about 81 kPa to about 91 kPa
(about 24 inches mercury to about 27 inches mercury) is typically pulled.
Once the vacuum is pulled, the entire mold and vacuum bag assembly is
placed into an oven (or otherwise heated) to cure the one or more layers
of uncured material 106. The temperatures used to cure the material will
depend upon the specific material utilized. Exemplary heating times range
from about 30 minutes to about 2 hours.

EXAMPLES

[0093]Exemplary embodiments and applications of the invention are
described in the following non-limiting examples and related testing
methods.

[0094]Tensile Testing Method

[0095]For tensile testing, samples were formed into standard tensile
testing specimens according to ASTM D638-95 using designations for Type
II measurements. Tensile testing was performed according to ASTM D638-95.
The rate at which the jaws holding the specimen were pulled in a tensile
manner was 1.0 millimeter/minute (0.04 inch/minute) to measure the
elastic modulus of the sample, but increased to 300 millimeters/minute
(11.8 inches/minute) to obtain the ultimate tensile strength and
elongation data. Test data using this method is reported in Table 1.

[0096]Recovery Testing Method

[0097]For recovery testing, a generally rectangular sample having an
initial length of 25 centimeters (10 inches) and width of 5 centimeters
(2 inches) was prepared. The sample was stretched in tension until its
length exceeded its initial length by a predetermined percentage (25% or
50%). After recovery equilibrium was obtained (approximately 5-10
minutes), the length of the relaxed sample was measured and the sample
was qualitatively analyzed for defects or deformation. The change in
length of the sample as compared to the initial length is reported as its
"Percent Deformation" in Table 2. Note that values reported in Table 2
have a standard deviation of about plus/minus 0.6%.

[0098]Elongation Force Testing Method

[0099]Force required to elongate a generally rectangular sample having an
initial length of 12.5 centimeters (5 inches) and width of 5 centimeters
(2 inches) was measured using an IMASS SP2000 slip/peel tester (available
from IMASS, Inc. of Accord, Mass.) operating at a speed of 30
centimeters/minute (12 inches/minute). Two forces were measured for each
sample, those being that required to elongate the sample to 125% of its
initial length and that required to elongate the sample to 150% of its
initial length. The forces so measured are also reported in Table 2.

[0100]Weathering Testing Method

[0101]Where indicated, samples were tested for weathering resistance using
a well-known QUV test method and weatherometer. The weathering conditions
were as set forth in ASTM D4329.

Example 1

[0102]An extensible polyurethane-based protective sheet was prepared such
that the sheet comprised a carrier layer having a thickness of 150
microns, a topcoat layer having a thickness of 18 microns, and an
adhesive layer having a thickness of 60 microns. The adhesive layer was
adhered to the opposite side of the carrier layer from the topcoat layer.
A standard release liner was positioned exterior to the adhesive layer,
but was removed prior to testing.

[0103]To prepare the sheet, first a 98# polyethylene-coated kraft paper
with silicone coated on one side was used as a release liner onto which
the adhesive layer was formed. The adhesive layer was formed from an
adhesive composition prepared by charging a closed vessel with initial
components as follows: 20% by weight 2-ethyl hexyl acrylate, 5% by weight
methyl acrylate, 1% by weight acrylic acid, 37% by weight ethyl acetate,
7% by weight isopropyl alcohol, 26.1% by weight toluene, and 3.75% by
weight n-propanol. The weight percentages of each component were based on
total weight of the reaction components, which also included 0.15% by
weight benzoyl peroxide (98%) added in partial increments. To the initial
components, 10% by weight of the benzoyl peroxide was first added. Then,
the components were charged under a nitrogen atmosphere and using
agitation. The vessel was heated at 80° C. until exotherm was
reached. The exotherm was maintained by addition of the remaining benzoyl
peroxide. After the benzoyl peroxide was depleted and the exotherm was
complete, aluminum acetal acetonate was added to the polymerized solution
in the amount of 0.4% by weight based on solid weight of the polymer.

[0104]This adhesive composition was coated onto the release liner and
dried in a 14-zone oven, at 20 seconds per zone, with the zone
temperatures set as follows: zone 1 (50° C.), zone 2 (60°
C.), zone 3 (70° C.), zone 4 (80° C.), zone 5 (90°
C.), zone 6 (90° C.), zones 7-10 (100° C.), and zones 11-14
(120° C.). With drying, the aluminum acetal acetonate functioned
to crosslink the polymer. The thickness of the adhesive layer thus formed
was 60 microns. The construction was then run through a chill stack to
reduce the temperature to about 30° C.

[0105]A 150-micron-thick film of extruded aliphatic polyurethane,
available from Stevens Urethane under the trade designation, SS-2219-92,
was then provided and laminated to the exposed adhesive layer. This
further construction was run through the 14-zone oven and then again
chilled to about 30° C.

[0106]Meanwhile, an 18-micron-thick film for the topcoat layer was formed
on a 76-micron thick (3-mil-thick) silicone-coated polyester carrier
film. The film was formed by solution coating the polyurethane-based
composition described below on the supporting carrier film. After the
composition was coated on the carrier film, it was run through the
14-zone oven and then chilled to about 30° C.

[0107]The polyurethane-based composition was prepared by charging a closed
vessel with 7.36% by weight of a hybrid linear hexane
diol/1,6-polycarbonate polyester having terminal hydroxyl groups, 43.46%
by weight toluene, 43.46% by weight isopropyl alcohol, and 0.03% by
weight dibutyl tin laureate. The weight percentages of each component
were based on total weight of the reaction components, which also
included 5.68% by weight isophorone diisocyanate added later. The
components were charged under a nitrogen atmosphere and using agitation.
After the vessel was heated to 90° C., 5.68% by weight isophorone
diisocyanate was continually added to the vessel through the resultant
exotherm. After the exotherm was complete, the composition was maintained
at 90° C. for one additional hour while still using agitation.

[0108]Once the topcoat layer was thus formed, it was thermally bonded to
the exposed surface of the carrier layer. During thermal bonding, the
carrier layer and the topcoat layer were contacted for about three
seconds with application of heat 150° C. (300° F.) and 140
Pa (20 psi) pressure. Prior to testing, the release liner and carrier
film were removed.

[0109]All of the individual components used in preparation of the
protective sheet are readily available from a variety of chemical
suppliers such as Aldrich (Milwaukee, Wis.) and others. For example, the
isopropyl alcohol and toluene can be obtained from Shell Chemicals
(Houston, Tex.).

[0110]Samples of the protective sheet were then tested according to the
Tensile Testing Method, Recovery Testing Method, and Elongation Force
Testing Method described above. Test data is reported in Table 1.
Further, samples of the protective sheet were tested according to the
Weathering Testing Method described above. After weathering for 500
hours, no visible yellowing was observed by the unaided human eye.
Finally, samples of the protective sheet were tested for deglossing by
placing them in an outside environment in the states of Florida and
Arizona for approximately one year. After one year, no visible deglossing
was observed by the unaided human eye.

[0111]For each example, a 150-μm (0.006-inch) thick film of a
polycaprolactone-based, aliphatic thermoplastic polyurethane film
(available from Argotec, Inc. of Greenfield, Mass.) is positioned as an
outer layer on top of four stacked layers of prepreg carbon fiber fabric.
The resulting 5-layer structure is then placed into a heated platen press
for a period of about 45 minutes, at a temperature of about 120°
C. (250° F.) and an applied pressure of about 0.34 MPa (50 psi).
During this step, the resin composition within the prepreg is cured. The
sample is then removed from the platen press and allowed to cool.

[0112]Any suitable epoxy resin composition can be used in this process. A
number of commercial suppliers and published documents provide
formulation guidelines for epoxy resin systems (e.g., "EPON® Resin
Chemistry" published by Resolution Performance Products). Most
Bisphenol-A and Bisphenol-F epoxy resins are expected to be suitable for
use as the epoxy resin according to these Examples 2A-2C. Most
amine-curing agents are expected to be suitable for use therein as well.

[0113]Resin Formulation 2A

[0114]As recommended in the company's data sheet for Amicure CG-1200 (an
amine curing agent available from Air Products and Chemicals, Inc. of
Allentown, Pa.), a suitable epoxy resin formulation is as follows:

[0115]Amicure CG-1200, in the amount of 4-15 phr (parts per hundred weight
epoxy resin), is added to an epoxy resin having an epoxide equivalent
weight (EEW) of 190. Numerous examples of Bisphenol-F and Bisphenol-A
epoxy resins with an EEW of approximately 190 are commercially available,
including for example, EPON Resin 828 (a Bisphenol-A epoxy resin
available from Resolution Performance Products of Houston, Tex.).

[0116]Resin Formulation 2B

[0117]As recommended in the company's data sheet for Amicure UR (an amine
curing agent available from Air Products and Chemicals, Inc. of
Allentown, Pa.), a suitable epoxy resin formulation is as follows:

[0118]Amicure CG-1200 (an amine curing agent available from Air Products
and Chemicals, Inc. of Allentown, Pa.), in the amount of 6 phr, is added
to an epoxy resin having an EEW of 190. Numerous examples of Bisphenol-F
and Bisphenol-A epoxy resins with an EEW of approximately 190 are
commercially available, including for example, EPON Resin 828 (a
Bisphenol-A epoxy resin available from Resolution Performance Products of
Houston, Tex.). In addition, Amicure UR cure accelerator (a substituted
urea-based accelerator available from Air Products and Chemicals, Inc. of
Allentown, Pa.) is added in the amount of 2 phr.

[0119]Resin Formulation 2C

[0120]As recommended in the company's data sheet for Ancamine 2441 (a
modified polyamine curing agent available from Air Products and
Chemicals, Inc. of Allentown, Pa.), a suitable epoxy resin formulation is
as follows:

[0121]Ancamine 2441 in the amount of 5 phr, is added to an epoxy resin
having an EEW of 190. Numerous examples of Bisphenol-F and Bisphenol-A
epoxy resins with an EEW of approximately 190 are commercially available,
including for example, EPON Resin 828 (a Bisphenol-A epoxy resin
available from Resolution Performance Products of Houston, Tex.). In
addition, Amicure CG-1200 (an amine curing agent available from Air
Products and Chemicals, Inc. of Allentown, Pa.), in the amount of 6 phr,
is added to the epoxy resin.

Example 3

[0122]Several layers of carbon fiber prepreg were prepared by hand-coating
sufficient epoxy thermoset resin into a 12K woven carbon fiber fabric.
The epoxy resin formulation was prepared based on 100 phr of EPON 863 (a
Bisphenol-F epoxy resin available from Resolution Performance Products of
Houston, Tex.), 22.4 phr of Ancamine 2441 (a modified polyamine curing
agent available from Air Products and Chemicals, Inc. of Allentown, Pa.),
and 5 phr of CAB-O-SIL TS-720 (a treated fumed silica available from
Cabot Corporation of Billerica, Mass.). A protective sheet was directly
bonded to the resulting epoxy-carbon fiber article using in-mold vacuum
bag processing. The protective sheet consisted of a 150-μm
(0.006-inch) thick film of a polycaprolactone-based, aliphatic
thermoplastic polyurethane film (available from Argotec, Inc. of
Greenfield, Mass. under the trade designation ARGOTEC 49510-6).

[0123]A flat aluminum plate was used as a vacuum bag mold surface. Prior
to configuring a vacuum bag assembly thereon, the aluminum plate was
cleaned and treated with the Waterworks Aerospace Release System
available from Waterworks of East Ellijay, Ga. The vacuum bag assembly
was constructed utilizing the following material components: Vacuum
Bagging Film (a modified nylon blue vacuum bagging film available from
The Composites Store, Inc. of Tehachapi, Calif.), Sealant Tape (available
from The Composites Store, Inc. of Tehachapi, Calif. under the
description "Yellow Super Seal Tacky Tape"), Breather Fabric (non-woven
polyester fabric available from Richmond Aircraft Products, Inc. of
Norwalk, Calif. under the trade designation, A 3000), Separator Release
Film (perforated, violet FEP fluorocarbon release film available from
Richmond Aircraft Products, Inc. of Norwalk, Calif. under the trade
designation, A5000 Release Film), Bleeder Fabric (non-woven polyester
fabric available from Richmond Aircraft Products, Inc. of Norwalk, Calif.
under the trade designation, A 3000), and Peel Ply Release Film
(PTFE-coated fiberglass fabric available from Airtech International, Inc.
of Huntington Beach, Calif. under the trade designation, RELEASE EASE
234TFP).

[0124]The protective sheet was placed adjacent the aluminum plate. Then,
four approximately 8-cm×13-cm (3-in×5-in) layers of the 12K
carbon fiber prepreg were stacked on the protective sheet for processing
in the vacuum bag assembly. After assembly of the vacuum bag system was
complete, a vacuum was pulled on the prepreg stack for about 10 minutes
to compress the various layers. While still pulling the vacuum, the
entire assembly was placed into an oven at 120° C. (250°
F.) for 60 minutes to cure the epoxy resin.

[0125]After cooling, the resulting carbon fiber composite articles were
removed. Upon visual inspection, it was noted that the protective sheet
was intimately bonded to the carbon fiber composite article. Surface
finish of the protective sheet mirrored that of the aluminum plate.

Example 4

[0126]Two layers of carbon fiber prepreg braid were prepared by hand
coating sufficient epoxy thermoset resin into a 3K-braided carbon fiber
sock. The epoxy resin formulation was prepared based on 100 phr of EPON
863 (a Bisphenol-F epoxy resin available from Resolution Performance
Products of Houston, Tex.), 22.4 phr of Ancamine 2441 (a modified
polyamine curing agent available from Air Products and Chemicals, Inc. of
Allentown, Pa.), and 5 phr of CAB-O-SIL TS-720 (a treated fumed silica
available from Cabot Corporation of Billerica, Mass.). A protective sheet
was directly bonded to the resulting epoxy-carbon fiber composite article
using a bladder molding process. The protective sheet consisted of a
single layer of 0.35-mm (0.014-inch) aliphatic polyurethane film
(available from Argotec, Inc. of Greenfield, Mass. under the trade
designation ARGOTEC 49510-14).

[0127]The tubular cavity of a two-piece aluminum mold was used to define
the outer surface of a lacrosse stick shaft to be formed from a composite
material. The mold was approximately 81 centimeters (32 inches) in length
and approximately 2.5 centimeters (1 inch) in diameter and was configured
as an octagonal shape, which is common to lacrosse stick shafts. Prior to
configuring the mold assembly, the protective sheet was applied to the
tubular cavity, which was first coated with FEP release agent. An
inflatable mandrel was constructed by fixturing a tubular latex bladder
(available from Latex Technology Inc. of San Marcos, Calif.) over a steel
tube attached to a supply of pressurized air. The prepreg braid was
placed over the inflatable mandrel and the assembly was inserted into the
mold cavity.

[0128]Pressurized air was applied to the inflatable mandrel causing the
bladder to inflate and moving the prepreg braid into contact with the
protective sheet against the mold surface. Pressure inside the bladder
was increased to 0.17 MPa (25 psi) in order to compress the layers of
prepreg braid and integrally bond the prepreg braid and the protective
sheet. The mold was heated 5° C. per minute to 120° C., at
which point it was held at 120° C. for 45 minutes to allow the
epoxy resin to cure.

[0129]After cooling, the resulting carbon fiber composite lacrosse stick
shaft was removed. Upon visual inspection, it was noted that the
protective sheet was integrally bonded to the carbon fiber composite
article. Surface finish of the protective sheet mirrored that of the
aluminum mold.

[0130]Various modifications and alterations of the invention will become
apparent to those skilled in the art without departing from the spirit
and scope of the invention, which is defined by the accompanying claims.
It should be noted that steps recited in any method claims below do not
necessarily need to be performed in the order that they are recited.
Those of ordinary skill in the art will recognize variations in
performing the steps from the order in which they are recited.